Ken Yamaguchi (山口 健, Yamaguchi Ken, March 24, 1956 – October 24, 2011) was a Japanese actor, voice actor and narrator. He was represented by OYS Produce. His son is a fellow voice actor Kiyohiro Yamaguchi (山口キヨヒロ, Yamaguchi Kiyohiro). He was most known for the roles of Ashuraman, The Omegaman, Prisman (Kinnikuman: Scramble for the Throne), Genji Togashi (Sakigake!! Otokojuku), Flazzard (Dragon Quest: Dai's Great Adventure), Black Dragon (Saint Seiya), and Ein (Fist of the North Star). Yamaguchi died on October 24, 2011, due to acute heart failure.